i883.] 



MICROSCOPICAL JOURNAL. 



25 



is the flour of the seeds of black mus- 

 tard and white mustard mixed in a 

 proportion that varies with the fancy 

 or honesty of each manufacturer ; 

 the black mustard seeds furnishing 

 the best mustard flour. To the mus- 

 tard flour is added a large proportion 

 of wheat flour, which serves to absorb 

 and retain the abundant oil of the 

 crushed mustard seeds, and it thus 

 ranks as commercially pure. A cele- 

 brated English manufacturer of mus- 

 tard uses 56 lbs. of wheat-flour to 112 

 lbs. of mustard-flour made from two 

 parts of black to one part of white 

 seed. This mixture is accepted as a 

 very superior article of "pure ground 

 mustard." In cheaper grades of mus- 

 tard the proportion of wheat-flour is 

 increased, the sifting out of the mus- 

 tard seed husks is less perfect, rye- 

 flour and other cheaper flours and 

 corn meal are used, and various adul- 

 terants are added, of which one of the 

 most common is turmeric, as it also 

 serves to darken the yellow color of 

 the mixture when much starchy flour 

 is used. 



The mustard seed itself is also sub- 

 ject to adulteration, but not exten- 

 sively, cheaper and harmless seeds 

 being mixed with it, clove seed being 

 the most common. The appearance 

 of the mustard seed under the micro- 

 scope is beautiful indeed, the surface 

 is covered with a net-work of raised 

 ridges enclosing shallow concave pits 

 of rudely hexagonal shape, smaller 

 and more irregular as they conve g*^ 

 toward the micropyle of the seed, and 

 containing a shrunken membrane- 

 like layer of glistening white substance 

 lining the sunken cavity, and in some 

 places looking like a flat scale-like 

 crystal lying in the pit, Plate V, fig. i. 

 The shell or husk of a dry seed ex- 

 amined in turpentine or water, exhibits 

 a rudely hexagonal areolation, and is 

 apparently thickly punctured with 

 small holes, and of a somewhat trans- 

 lucent red color, like colored horn, 

 fig. 2, a. The seed-shell is lined in- 

 side and out by a thin, close, cellular 

 membrane, the outer one with very 



much larger cells than the inner, and 

 having a dinted appearance, Fig. 2, c. 

 The inner membrane is enti'"el)' 

 hyaline and glass-like, and when 

 viewed on the inside of the dry seed- 

 shell, by lieberkuhn, it appears to be 

 the inner surface of the husk itself, 

 composed of small irregular cells 

 having a sunken appearance and a 

 bright blood-red color. This inner 

 membrane, in fact, adheres so closely 

 to the shell as to almost universally 

 follow its fracture, and so is seldom 

 seen projecting from ihe broken edge 

 of the husk as the outer membrane 

 often is, (fig. 2, <:,) but on taking a seed 

 that has been soaked for a day or so 

 in water, or for a short time in dilute 

 nitric acid, and squeezing out the 

 cotyledon, the outer and inner mem- 

 branes will be found swelled and 

 softened, and can be scraped off with 

 needles and examined separately. 

 The inner one then appears as in fig. 

 12, d, and the outer one, much more 

 swollen, as in fig. 12, c. 



The structure of the substance of 

 the seed-shell is very peculiar and 

 complex, and more space than is at 

 command would be required to de- 

 scribe it fully. Its appearance, so far 

 as identification is concerned, is, how- 

 ever, distinctive and easily recognized. 

 When untreated the shell presents in 

 water, turpentine, or glycerin, the 

 appearance shown in fig. 2, d, when 

 viewed with the inner surface upper- 

 most : the ridges of the outer surface 

 (J)) are indistinctly seen through the 

 shell, which appears to be composed 

 of rudely hexagonal blocks contain- 

 ing, each, several of the small holes 

 (a) with the large-celled, mottled or 

 dinted outer membrane {c) projecting 

 in places. The appearance of hexag- 

 onal blocks is caused by the cell-walls 

 of the inner membrane, for when this 

 is scraped off, no such appearance is 

 seen (fig. 2, a). By soaking the shell 

 in potash or acid it is made apparent 

 that each hole is in a separate block, 

 for these are clearly seen, fig. 12, a, 

 and can be picked apart with needles, 

 fig. 12,/; The seed-shell has, however, 



